WO2017171805A1

WO2017171805A1 - Classifying interference in power line devices

Info

Publication number: WO2017171805A1
Application number: PCT/US2016/025327
Authority: WO
Inventors: Ioannis Pefkianakis; Kamran Ali ALI
Original assignee: Hewlett Packard Enterprise Development Lp
Priority date: 2016-03-31
Filing date: 2016-03-31
Publication date: 2017-10-05

Abstract

Examples relate to classifying interference in power line devices. In one example, a computing device may: obtain, from a power line device, physical layer feedback, the physical layer feedback including a tonemap that specifies, for each of a plurality of signal subcarriers, a number of modulated bits; and classify, using the obtained tonemap, the physical layer feedback as one of a plurality of types of physical layer feedback.

Description

CLASSIFYING INTERFERENCE IN POWER UNE DEVICES

BACKGROUND

[0001] Power Line Communication (PLC) technology is form of communications that uses electrical wiring to carry both data and Alternating Current (AC) to various devices. PLC devices, e.g., adapters that plug into a home or office power outlet, may be used to form PLC networks, which can be used to transmit data between devices connected to the PLC devices. For example, a PLC device may be used to extend data communications from one portion of a building to another, using existing power lines as opposed to Wi-Fi range extenders, coaxial cables, twisted pair cabling, and other alternatives. Despite potential interference issues with PLC communications, PLC technology may offer some entities an additional form of network communications that may be preferable to the alternatives.

BREF DESCRIPTION OF THE DRAWINGS

[0002] The following detailed description references the drawings, wherein:

[0003] FIG. 1 is a block diagram of an example computing device for classifying interference in power line devices.

[0004] FIG. 2 is a data flow depicting the classification of interference in a power line device.

[0005] FIG. 3 depicts an illustration of an example tonemap used to classify interference in power line devices.

[0008] FIG. 4 is a flowchart of an example method for classifying interference in power line devices.

DETAILED DESCRIPTION

[0007] Power Line Communications (PLC) devices often face interference, such as time-varying background noise, variable channel attenuation, and potentially significant multipath frequency-selective fading due to branching and unmatched loads connected to those branches. Interference may come from a variety of sources, and the ability to classify various types of interference in a PLC device or network may facilitate a variety of functions, such as PLC device placement throughout a particular location, power use monitoring, and/or power management. In particular, tonemaps provided by PLC devices may be used to classify various types of interference.

[0008] For example, PLC devices measure physical layer feedback and produce tonemaps that specify the number of modulated bits for each signal subcarner used by the PLC device. Multiple signal subcarriers may be used to transmit data within a single channel, e.g., using orthogonal frequency-division multiplexing (ODFM), and the number of modulated bits may indicate signal quality for particular signal subcarriers. For example, a relatively high number of modulated bits would indicate a relatively high quality signal for a particular signal subcarrier, while a relatively low number of modulated bits would indicate a relatively low quality signal for another signal subcarrier. The signal quality per subcarrier, e.g., number of modulated bits per subcarrier, may be affected by a variety of things, such as interference from other devices connected to the electrical network.

[0009] Tonemaps obtained from a particular PLC device may be used to classify various sources of interference, or physical feedback. For example, a baseline tonemap, which indicates signal quality without interference from other devices, may be established for a PLC device or pair of PLC devices. When sources of electrical interference affect signal for the PLC device(s), the interference may be measured in one or more tonemaps. As discussed in further detail below, the tonemaps may be used to train a classifier, which can then be used to classify sources of interference based on tonemaps.

[0010] Referring now to the drawings, FIG. 1 is a block diagram 100 of an example computing device 110 for classifying interference in power line devices. Computing device 110 may be, for example, a power line adapter or other power line device, or a computing device connected to the power line network, such as a personal computer, a server computer, or any other similar electronic device capable of communicating with PLC network devices. In the example implementation of FIG. 1 , the computing device 110 includes a hardware processor, 20, and machine-readable storage medium, 130.

[0011] Hardware processor 120 may be one or more central processing units (CPUs), semiconductor-based microprocessors, and/or other hardware devices suitable for retrieval and execution of instructions stored in machine-readable storage medium, 130. Hardware processor 120 may fetch, decode, and execute instructions, such as 132-138, to control processes for classifying interference in power line devices. As an alternative or in addition to retrieving and executing instructions, hardware processor 120 may include one or more electronic circuits that include electronic components for performing the functionality of one or more instructions.

[0012] A machine-readable storage medium, such as 130, may be any electronic, magnetic, optical, or other physical storage device that contains or stores executable instructions. Thus, machine-readable storage medium 130 may be, for example, Random Access Memory (RAM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a storage device, an optical disc, and the like. In some implementations, storage medium 130 may be a non- transitory storage medium, where the term "non-transitory" does not encompass transitory propagating signals. As described in detail below, machine-readable storage medium 130 may be encoded with executable instructions: 132-138, for classifying interference in power line devices.

[0013] FIG. 1 also depicts a separate power line device 140, such as a power line adapter. While the power line device 140 is depicted separately from the computing device 110, in some implementations the computing device 110 may be or may be included in the power line device 140, e.g., such that the power line adapter executes instructions 132-138.

[0014] As shown in FIG. 1 , the hardware processor 120 executes instructions 132 to obtain, from the power line device 140, tonemaps 150 that each specify a number of modulated bits per signal subcarrier, each of the tonemaps 50 being measured by the power line device 140 at a different point in time. The power line device 140 may be part of a pair of power line devices thai forms a PLC network. In some implementations, tonemaps 150 may be logged by one PLC device and provided to another PLC device. In some implementations, at least some of the tonemaps 150 may be provided to the computing device 110 manually, e.g., provided by the power line device 140 in response to user input. For example, a user may cause the power line device 140 to send each of the tonemaps 150 at a particular point in time, e.g., when certain known sources of PLC interference are active and/or inactive. For example, one of the tonemaps 150 may be a baseline or reference tonemap that is measured when no known sources of PLC interference between PLC device pairs is known, another may be measured when a single known source of interference is active, and yet another may be measured when two distinct sources of interference are active.

[0015] The hardware processor 120 executes instructions 134 to analyze the tonemaps 150 to determine feedback profiles, each feedback profile i) being different from each other feedback profile, and ii) corresponding to at least one of the tonemaps 50. For example, differences in tonemaps may be associated with different types of interference, and profiles may be created for each different tonemap. in some implementations, feedback profiles may be determined based on one or more characteristics represented in a tonemap or tonemaps, such as a number of affected subcarriers, the number of modulated bits, and/or a pattern of change over time observed in the tonemaps. For example, turning on a lamp that is near a PLC device may cause interference for a set of signal subcarriers, which may be identified in a particular tonemap by a decrease in modulated bits across the set of signal subcarriers. After analyzing the particular tonemap, a feedback profile may be created and associated with the particular tonemap.

[0018] in some implementations, the computing device 110 may obtain, for each of the tonemaps 150, an interference source identifier that identifies a source of interference for the tonemap. Each obtained interference source may be associated with a feedback profile. For example, a lamp, refrigerator, microwave, or other source of electrical interference may be associated with an identifier, and the feedback profile created for each source may be associated with corresponding source identifiers, in some implementations, a feedback profile may be associated with multiple source identifiers, e.g., both a lamp and a refrigerator. Source identifiers may be obtained in a variety of ways. For example, a user may manually enter source identifiers, e.g., concurrently with activation of the corresponding interference source. As another example, the computing device 110 may automatically label new interference sources, e.g., sources having a tonemap not previously recorded by the power line device 140, with an identifier, e.g., sequential numbers or letters. As described in further detail below, source identifiers may provide a mechanism for identifying the source of new and previously encountered forms of interference.

[0017] in some implementations, the computing device 110 may determine, for the power line device 140, a power line device profile that specifies, for at least one point in time, interference source identifiers for each source of interference active at each point in time. For example, the computing device 0 may obtain tonemaps 150 from the power line device 140 over a period of time, such as one day, and use the tonemaps 150 to determine an expected device profile for the power line device 140. This may include, by way of example, an average or median number of modulated bits per subcarrier over the day, variance in modulated bits per subcarrier across all or a subset of the signal subcarriers, and/or an expected tonemap for any given period of time through the day. For example, the computing device 1 0 may build a device profile that would indicate, for any given time throughout a day, the expected tonemap and the source identifiers of the expected sources of interference at each given time. This may facilitate a variety of functions, such as the prediction of power line usage, analysis of interference source usage, and identification of interference outliers.

[0018] The hardware processor 120 executes instructions 138 to obtain, from the power line device 140, a new tonemap 152. The new tonemap 152 may be, for example, obtained at a later time than the original tonemaps 150. As with the original tonemaps 150, the new tonemap also specifies, for each of the plurality of signal subcarriers, a number of modulated bits per subcarrier.

[0019] The hardware processor 120 executes instructions 138 to classify the new tonemap 152 based on the feedback profiles. In some implementations, the new tonemap 152 is classified by identifying a matching tonemap from the original tonemaps 150 and classifying the new tonemap 152 as being of a type associated with the matching tonemap. By way of example, in a situation where one of the tonemaps 150 includes a particular tonemap that specifies interference while a lamp is activated near the power line device 140, a new tonemap 152 that matches the particular tonemap may be classified as being of the same type as the particular tonemap. In implementations where source identifiers are used, the new tonemap 152 may also be labeled or otherwise associated with an interference source, e.g., a lamp. As used herein, a tonemap match does not require an exact match, but may include substantial similarity or similarity within a certain threshold, e.g., 90% of modulated bits match.

[0020] As noted above, using tonemaps to classify interference in power line devices may facilitate a variety of network and power related functions. For example, classifying interference may facilitate optimization of a power line network, e.g., by enabling the placement of power line devices and/or sources of power line interference throughout a building in a manner design to optimize or improve power line network bandwidth, throughput, and/or power usage. As another example, interference profiles may be used to identify and/or label new or previously unknown sources of power line interference. In addition, the ability to identify sources of power line interference may also facilitate power monitoring, e.g., by enabling a user or monitoring device to identify active sources of interference at any given time.

[0021] FIG. 2 is a data flow 200 depicting the classification of interference in a power line device 210. The power line device 210 may be the same as or similar to the power line device 140 of FIG. 1. In addition to the power line device 210, the data flow 200 includes an interference classification device 220, feedback profile storage 230, and an output device 240. The interference classification device 220 may be any computing device, such as the computing device 1 10 of

FIG. 1. While each device is shown separately in the data flow 200, in some implementations some or ail of the devices - the power line device 210, interference classification device 220, feedback profile storage 230, and output device 240 - may be included in a single device, such as a power line adapter. [0022] The interference classification device 220 receives physical layer feedback, e.g., in the form of a tonemap 212, from a power line device 210. The tonemap 212 specifies, for each signal subcarrier, a number of modulated bits. Tonemaps may be expressed in a variety of ways and, in some implementations, the tonemaps may be expressed as depicted in the example illustration of FIG. 3, discussed in further detail below.

[0023] The interference classification device 220 classifies the feedback being experienced by the power line device 210 using the tonemap 212. Classification involves, for example, identifying the physical layer feedback as one of multiple different types of feedback. In the example data flow 200, the interference classification device 220 is in communication with feedback profile storage 230, which may be any type of storage device, such as the computer readable storage medium 130 of FIG. 1. Feedback profile storage 230 includes feedback profiles, such as profiles 232, 234, and 236, each of which define a variety of different types of physical layer feedback, or interference.

[0024] The example profiles include a lamp profile 232, which specifies, for each of the subcarriers, a number of modulated bits. Similarly, a microwave profile 234, refrigerator profile 236, and any other profiles, may specify modulated bits for each signal subcarrier used by the power line device 210. In some implementations, feedback profiles, or types of physical layer feedback, may be identified by analyzing tonemaps obtained from the power line device 210 over time. As noted above, the number of affected subcarriers in a single tonemap or across multiple tonemaps over time, the number of modulated bits in a single tonemap or across multiple tonemaps over time, and/or a pattern of change across multiple tonemaps over time may ail be used to determine and define feedback profiles.

[0025] While each example profile in the data flow 200 specifies a static number of modulated bits per subcarrier, in some implementations profiles may specify additional and/or different data to define a given feedback profile. For example, in situations where certain types of physical layer feedback, or feedback profiles, are determined using multiple tonemaps over a given period of time, feedback profiles may specify a pattern of change over time in affected subcarriers and/or modulated bits. In these situations, the interference classification device 220 may obtain multiple tonemaps from the power line device 210, e.g., over time, to attempt to match a feedback profile. By way of example, the feedback profile for a vending machine may specify a particular pattern of change in a subset of the subcarriers over time, e.g., the subset of subcarriers may alternate between 2 and 8 modulated bits every 5 minutes while the vending machine is powered on.

[0026] in some implementations, the interference classification device 220 may associate feedback profiles with interference source identifiers. For example, in situations where feedback profiles are determined by analyzing tonemaps received over time, different profiles may be associated with different source identifiers which identify the source of physical interference associated with the corresponding tonemap(s). As noted above, the source identifiers may be chosen in a variety of ways, e.g., a predetermined identifier scheme to assign identifiers to each different profile, and/or using identifiers obtained from user input.

[0027] After classifying the physical layer feedback experienced by the power line device 210, the interference classification device 220 sends the classification 222 as output to an output device 240. The output device 240, as noted above, may be a separate device or may be included in a single device, e.g., within a power line adapter. For example, the output device 240 may be a personal computer or server computer connected to the same network that the power line device 210 is operating in. In another example, the output device may be a logging component of an power line adapter, which may be accessed by a third party computing device or output on a display device of the power line adapter.

[0028] in some implementations, the interference classification device 220 classifies physical layer feedback using a baseline tonemap obtained from the power line device 210. A baseline tonemap may be, for example, a tonemap provided by the power line device 210 when no known sources of interference exist. A baseline tonemap may be used to classify the tonemap 212, for example, by selectively choosing to classify only tonemaps that deviate from, or do not match, the baseline tonemap. [0029] FIG. 3 depicts an illustration of an example tonemap 300 used to classify interference in power line devices. The horizontal axis of the tonemap 300 indicates signal subcarriers by numbered identifier while the vertical axis indicates modulation, or the number of modulated bits per subcarrier. The example tonemap 300 a relatively strong signal from subcarriers 1-150, weakening signal strength from subcarriers 150-400, and relatively strong signal from subcarriers 400-950. The number of subcarriers used, and the range of modulation, may depend on the communications protocol being used. PLC devices may, for example, use CSMA/CA AC-layer protocols to access the power line communication medium, which is based on an orthogonal frequency division multiplexing (OFDM) scheme using 917 signal subcarriers.

[0030] FIG. 4 is a flowchart of an example method 400 for classifying interference in power line devices. The method 400 may be performed by a computing device, such as a computing device described in FIG, 1 , e.g., in the form of a power line adapter or personal computer. Other computing devices may also be used to execute method 400. Method 400 may be implemented in the form of executable instructions stored on a machine-readable storage medium, such as the storage medium 130, and/or in the form of electronic circuitry.

[0031] A first tonemap that specifies a number of modulated bits for each of a plurality of signal subcarriers is obtained from a power line device (402). As noted above, the tonemap may be produced by one or a pair of power line devices.

[0032] From a plurality of feedback profiles, a feedback profile that specifies a matching tonemap that matches the first tonemap is identified (404). For example, a power line device may store feedback profiles that are based on previously measured tonemaps. The power line device may compare tonemaps to identify a feedback profile that includes a similar or matching tonemap.

[0033] in some implementations, multiple tonemaps are measured by a power line device at different points in time, and the tonemaps may be analyzed to determine the feedback profiles. Each feedback profile i) is different from each other feedback profile, and ii) corresponds to at least one of the tonemaps. In some implementations, feedback profiles may be determined based on i) a number of affected subcarriers identified in at least one tonemap, ii) a number of modulated bits specified by at least one tonemap, and/or iii) a pattern of change over time observed in at least one tonemap. For example, regular variations in modulation of particular subcarriers may be an observed pattern that is associated with a particular feedback profile. In situations where multiple tonemaps are used to generate feedback profiles, multiple tonemaps may be obtained from the power line device in order to attempt to match tonemaps with one of the feedback profiles.

[0034] One or more sources of interference are determined based on the identified feedback profile (406). In some implementations, some tonemaps may be associated with one or more interference source identifiers that identify a source of interference for the tonemap. For example, user input may be used to specify, for a particular tonemap, which active device(s) may have caused interference, e.g., due to proximity to a power line device pair, in this situation, feedback profiles may be associated with interference sources, e.g., when a user identifies a tonemap as a tonemap that was measured while a lamp was active near the power line device, the feedback profile created using that tonemap may specify that the lamp near the power line device was the cause of interference indicated in the corresponding tonemap.

[0035] In some implementations, a power line device profile may be determined for the power line device. A power line device profile specifies, for at least one point in time, interference source identifiers for each source of interference active at the at least one point in time. For example, a power line device profile may be able to provide a snapshot of active or expected sources of interference at any given time using feedback profiles. Expected sources of interference may be determined based on historical measurements taken by the power line device and may be used, for example, to predict which sources of interference may be active at a given time. Predicting sources of interference may be used to facilitate placement of power line devices in a manner designed to minimize interference at particular points in time. Device profiles may, in some implementations, be measured at different physical locations, and the device profiles may then also be used to facilitate placement of power line devices. [0036] In some implementations, a power line device implementing the method 400 above may also provide output to a separate device, such as a separate personal computer, server computer, or mobile device. This may facilitate monitoring a variety of power line information, such as PLC network performance/interference, power consumption, and in some implementations may be used to identify which particular sources of interference may be active at any point in time.

[0037] While the method 400 is described with respect to a power line device, other computing devices may also be used for performing some or ail of the above features. For example, a server computer may collect tonemaps and perform the analysis to create feedback profiles.

[0038] The foregoing disclosure describes a number of example implementations for classifying interference in power line devices. As detailed above, examples provide a mechanism for creating a classifier and classifying PLC network interference using tonemaps produced by power line devices.

Claims

CLAiMS We claim:

1. A computing device for classifying interference in power line devices, the computing device comprising:

a hardware processor; and

a data storage device storing instructions that, when executed by the hardware processor, cause the hardware processor to:

obtain, from a power line device, physical layer feedback, the physical layer feedback including a tonemap that specifies, for each of a plurality of signal subcarriers, a number of modulated bits; and

classify, using the obtained tonemap, the physical layer feedback as one of a plurality of types of physical layer feedback.

2. The computing device of claim 1 , wherein the instructions further cause the hardware processor to:

obtain, from the power line device, a baseline tonemap that specifies, for each of the plurality of signal subcarriers, a number of modulated bits at a first point in time, and

wherein the physical layer feedback is classified using the baseline tonemap.

3. The computing device of claim 1 , wherein the instructions further cause the hardware processor to:

obtain, from the power line device, a plurality of tonemaps, each of the plurality of tonemaps being measured by the power line device at a different point in time; and

analyzing the plurality of tonemaps to select the plurality of types of physical layer feedback, each type of physical layer feedback corresponding to at least one of the plurality of tonemaps.

4. The computing device of claim 3, wherein each type of physical later feedback is selected based on at least one of:

a number of affected subcarriers identified in at least one tonemap;

a number of modulated bits specified by the at least one tonemap; or a pattern of change over time observed in the at least one tonemap.

5. The computing device of claim 3, wherein the instructions further cause the hardware processor to:

obtain, for each of the plurality of tonemaps, an interference source identifier that identifies a source of interference for the tonemap, and

wherein each type of physical layer feedback corresponds to at least one interference source.

8. A non-transitory machine-readable storage medium encoded with instructions executable by a hardware processor of a computing device for classifying interference in power line devices, the machine-readable storage medium comprising instructions to cause the hardware processor to:

obtain, from a power line device, a plurality of tonemaps that each specify a number of modulated bits per signal subcarrier, each of the plurality of tonemaps being measured by the power line device at a different point in time; and

analyze the plurality of tonemaps to determine a plurality of feedback profiles, each feedback profile i) being different from each other feedback profile, and ii) corresponding to at least one of the plurality of tonemaps;

obtain, from the power line device, a new tonemap; and

classify the new tonemap based on the plurality of feedback profiles.

7. The storage medium of claim 8, wherein the new tonemap is classified by:

identifying, from the plurality of tonemaps, a matching tonemap that matches the new tonemap; and

classifying the new tonemap as being of a type associated with the matching tonemap,

8. The storage medium of claim 6, wherein each feedback profile is determined based on at least one of:

a number of affected subcarriers identified in at least one tonemap;

9. The storage medium of claim 6, wherein the instructions further cause the hardware processor to:

obtain, for each of the plurality of tonemaps, an interference source identifier that identifies a source of interference for the tonemap; and

associate each feedback profile with at least one interference source.

10. The storage medium of claim 9, wherein the instructions further cause the hardware processor to:

determine, for the power line device, a power line device profile that specifies, for at least one point in time, interference source identifiers for each source of interference active at the at least one point in time.

11. A method for classifying interference in power line devices, implemented by a hardware processor, the method comprising:

obtaining, from a power line device, a first tonemap that specifies a number of modulated bits for each of a plurality of signal subcarriers;

identifying, from a plurality of feedback profiles, a feedback profile that specifies a matching tonemap that matches the first tonemap; and

determining one or more sources of interference based on the identified feedback profile.

12. The method of claim 11 , further comprising:

obtaining a plurality of tonemaps that each specify a number of modulated bits per signal subcarrier, each of the plurality of tonemaps being measured by the power line device at a different point in time; and analyzing the plurality of tonemaps to determine the plurality of feedback profiles, each feedback profile i) being different from each other feedback profile, and ii) corresponding to at least one of the plurality of tonemaps.

13. The method of claim 12, where in each feedback profile is determined based on at least one of:

a number of affected subcarriers identified in at least one tonemap;

14. The method of claim 12, further comprising:

obtaining, for each of the plurality of tonemaps, an interference source identifier that identifies a source of interference for the tonemap; and

associating each feedback profile with at least one interference source.

15. The method of claim 14, further comprising:

determining, for the power line device, a power line device profile that specifies, for at least one point in time, interference source identifiers for each source of interference active at the at least one point in time.